The names wont ever change, and for quite a few good reasons:
1 Have two different types of Uranium would make no sense at all. With how you described U235, they would have to change what Plutonium does.
1a That isnt happening because some saves out there require the reaction plutonium has with neutrons. Have you seen the bomb in Destoyable City 5? Wouldnt work if Plutonium changed.
2 That would be more work for devs. They would probably have to make it so that both U238 and U235 are created by smashing together protons. The amount of energy+amount of protons needed to do each would have to be fairly close, right? Too close for it to really matter.
3 If devs didnt change plutonium, then you have two elements that do the same exact thing. Pointless. We already have quite a few elements that are pointless as it is. I dont think we need more.
4 Putting different isotopes into a game is not going to happen. It makes the game too much to take.
That is my reasoning. Thank you.
BUT PLUT IS BORING :'( :P